KR100960486B1 - Image processing apparatus, image processing method, image forming apparatus, image forming method, and recorded material - Google Patents

Abstract

An image processing apparatus according to the present invention includes an image input unit 11 for inputting main image information defined by first, second, and third color component information corresponding to at least three colors, and a color difference grid pattern as sub information. The modulating unit 16 for modulating, and each of the modulated chrominance grid pattern and the first, second, and third color component information are rotated with respect to each other at a predetermined angle, and then the first and second modulated chrominance grid patterns are rotated. And a superimposition unit 16 overlapping each of the third color component information, and a combining unit 16 for synthesizing the first, second and third color component information to generate the color image information.

Image processing, main image information, color component information, color difference grid pattern, color image information

Description

IMAGE PROCESSING APPARATUS, IMAGE PROCESSING METHOD, IMAGE FORMING APPARATUS, IMAGE FORMING METHOD, AND RECORDED MATERIAL}

The present invention is, for example, an image processing apparatus and image processing method for superimposing another additional sub information (such as security information) on color image information (such as a human face image) as main information. It is about.

The invention also relates to an image forming apparatus and an image forming method for forming color image information in which sub information is superimposed on a recorded material by using an image processing apparatus and an image processing method.

The present invention also relates to a recording produced using the image processing apparatus and the image processing method.

The present invention also relates to an image processing apparatus and an image processing method for reproducing sub information from a recording produced using the image processing apparatus and the image processing method.

Recently, with the digitization of information and the spread of the Internet, techniques such as digital watermarks and digital signatures for preventing forgery and modulation of images have been recognized. The digital watermark technique embeds sub information (sub picture information) in addition to the main information (main picture information) in an invisible state. This digital watermark technique has been proposed as a countermeasure against illegal copying, forgery, and forgery of personal authentication media such as ID cards and photographs embedded with copyright information.

For example, Japanese Patent Application Laid-open No. Hei 9-248935 proposes a digital watermark embedding method for embedding data in image data to be output on printed matter using characteristics of high spatial frequency components and color difference components that are difficult for humans to recognize. .

In addition, Japanese Laid-Open Patent Publication No. 2001-268346 proposes a printing apparatus for digital watermark that can be confirmed by an optical filter.

This digital watermark embedding processing method can embed sub information (sub picture information) in the invisible state in the main information without any deterioration by using the following description.

(1) human visual characteristics

The tone discrimination ability decreases as the frequency of the picture increases.

Color difference information is harder to distinguish than luminance information.

(2) Example of complementary color relationship: red + cyan = (for additional color blending) achromatic (white)

(3) high frequency carrier pattern image + complementary color relationship and color difference information

As an example of (2), in the case of additional color mixing, red and cyan (= green + blue) have a complementary color relationship, and even neighboring red and cyan are very difficult to distinguish with the naked eye, and are recognized as achromatic.

As an example of (3), a high-frequency carrier pattern image is formed by a color difference grid pattern in which red and cyan-rich pixels are repeatedly assigned, which indicates that the subtle color difference cannot be visually distinguished and the amount of color difference is determined evenly. Use visual characteristics.

If the authenticity determination of the recording in which the image is recorded by applying the aforementioned digital watermark technique is required, the sub information recorded in the recording is reproduced using the key information, as described in the two references mentioned above. Similarly, authenticity is determined based on the reproduction result of the sub information.

Specifically, input devices such as scanners and cameras read composite image information in which sub information as color difference information is embedded. Next, the image processor reproduces the sub information from the synthesized image information using a digital filter having a frequency component corresponding to specific frequency information of the key information, and then checks authenticity based on the reproduced result.

However, the above technique has the following problems. That is, the electrophotographic method is modified as a recording method for a general digital copying machine or the like. The electrophotographic method enables high speed printing capable of recording color images at several tens of ppm or more. The electrophotographic method forms a color image using four color toners of yellow, magenta, cyan and black. In forming a color image using these four colors, a dark blue method of expressing a color image by superimposing pixels of each color can be used. However, in the case of high speed printing, it is difficult to accurately overlap each color pixel. If each pixel does not overlap correctly, color misregistration occurs.

In order to solve this problem, for example, the following method is known. That is, the arrangement direction of the plurality of magenta pixels, the arrangement direction of the plurality of cyan pixels, and the arrangement direction of the plurality of black pixels are given as tilts at different angles with respect to the arrangement direction of the plurality of yellow pixels. These plurality of yellow, magenta, cyan and black pixels are then synthesized to represent a color image. As a result, a color image can be formed without accurately overlapping the inks. Therefore, color mismatch can be prevented when the pixel is separated.

However, the arrangement direction of the plurality of pixels forming the color difference grid pattern does not correspond to the arrangement direction of the plurality of magenta, cyan and black pixels. Therefore, when such a color difference grid pattern is modulated by the sub information and color image information superimposed with the modulated color difference grid pattern is printed by the electrophotographic method, the color difference grid pattern is disturbed. That is, the sub information cannot be superimposed properly on the color image information.

In contrast, Japanese Laid-Open Patent Publication No. 2004-328217 proposes a method of superimposing a color difference grid pattern modulated by sub information on main information formed by alternating driving to alternately form pixels for each recording line. This reference describes that after sub information is embedded in each part of the RGB image information with a tilt of a predetermined angle in a preset direction, each part of the RGB image information in which the sub information is embedded is preset in a direction opposite to the preset direction. A method of alternately forming pixels for each recording line by giving a tilt of a set angle is disclosed. In this way, however, all the R, G and B colors have a common tilt angle, and the pixels are formed by alternating driving. For this reason, this method does not solve the aforementioned problem in the screening method in which the arrangement directions of the plurality of color pixels are different.

It is therefore an object of the present invention to provide an image processing apparatus and an image processing method capable of properly superimposing main information and sub information using a screening method in forming a color image.

It is another object of the present invention to provide an image forming apparatus and an image forming method capable of generating superimposed images by appropriately superimposing main information and sub information using a screening method in forming a color image.

It is still another object of the present invention to provide a recording which records a superimposed image formed by appropriately superimposing main information and sub information using a screening method in forming a color image.

It is still another object of the present invention to provide an image processing apparatus and an image processing method capable of accurately reproducing sub information from printed matter recording superimposed images formed by appropriately superimposing main information and sub information using a screening method in forming a color image. To provide.

An image processing apparatus according to an embodiment of the present invention includes image input means for inputting main image information defined by first, second and third color component information corresponding to at least three colors, and a color difference grid as sub information. Modulating means for modulating the pattern, the modulated chrominance grid pattern and the first, second and third color component information respectively rotate relative to each other at a predetermined angle, and then modulate the modulated chrominance grid pattern to the first and second. And superimposing means for superimposing each of the third color component information, and synthesizing means for synthesizing the first, second and third color component information superimposed with the color difference grid pattern modulated to generate the color image information.

An image processing method according to an embodiment of the present invention includes the steps of inputting main image information defined by first, second and third color component information corresponding to at least three colors, and a color difference grid pattern modulated by sub information. And rotating each of the first, second, and third color component information with respect to each other at a predetermined angle, and then superimposing the modulated chrominance grid pattern on each of the first, second, and third color component information; Synthesizing the first, second, and third color component information superimposed with the chrominance grid pattern modulated to produce image information.

A recording according to an embodiment of the present invention includes color image information, and the color image information includes a color difference grid pattern modulated by sub information, main image information, and corresponding to at least three colors. Each of the second and third color component information is rotated relative to each other at a predetermined angle, and then modulated to superimpose the modulated chrominance grid pattern on each of the first, second and third color component information, and generate color image information. Information generated by synthesizing the first, second and third color component information superimposed on the chrominance grid pattern.

An image processing apparatus according to an embodiment of the present invention processes color image information, and the image processing apparatus includes reading means for reading color image information from a recording in which the color image information is recorded, and a first image from the color image information. Color separation means for separating the second and third color component information, individual color rotation means for rotating the first, second and third color component information at a predetermined angle, and rotation based on the color difference grid pattern. Sub information extracting means for extracting sub information from the first, second, and third color component information.

An image processing method according to an embodiment of the present invention processes color image information, and the image processing method includes the steps of reading color image information from a recording in which color image information is recorded, Separating the second and third color component information, rotating the first, second and third color component information at a predetermined angle, and rotating the first, second and third based on the color difference grid pattern. Extracting the sub information from the color component information.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be embodied and obtained by means and combinations particularly pointed out herein.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the foregoing general description and detailed description of the embodiments set forth below, serve to explain the principles of the invention.

Each embodiment will be described below with reference to the accompanying drawings.

First, a first and second color image representation method for representing a color image by tilting the pixel formation direction of each color at a predetermined angle will be described.

The first color image representation method will be described first. Fig. 29 shows an example of the color image 5 formed on the recording 4 by the electrophotographic method. FIG. 30 is a partially enlarged view of a portion 5a of the color image 5 shown in FIG. 29, and FIG. 31 shows respective parts of the separated color component information shown in FIG. As shown in Figs. 30 and 31, the pixel formation directions of yellow (Y) color component information, magenta (M) color component information, cyan (C) color component information, and black (K) color component information are respectively 0 ° ( (Hereinafter referred to as screen angle), a method of forming a color image while providing halftone for each color by tilting it at 45 °, 15 ° and 75 ° (these methods are later referred to as screening methods). .

The second color image representation method will be described below. 32 is a partial enlarged view of a portion 5a of the color image 5 shown in FIG. 29, and FIG. 33 shows respective portions of the separated color component information shown in FIG. As shown in FIGS. 32 and 33, the pixel formation directions of the yellow (Y) color component information, magenta (M) color component information, cyan (C) color component information, and black (K) color component information are respectively 108.4 ° ( (Hereinafter referred to as screen angle), -18.4 °, 18.4 ° and 0 ° to form a color image while providing halftone for each color (this method will be referred to as screening method later).

Since the color image can be formed without accurately superimposing the ink by such first and second color image representation methods, occurrence of any color mismatch can be prevented when leaving the pixel.

The first embodiment will be described below.

The first embodiment is applied to the case of the first color image representation method described above with reference to FIGS. 30 and 31.

1 shows a schematic configuration of an image processing system to which an image processing apparatus and an image processing method for embedding sub information according to the first embodiment are applied. Such an image processing system includes an image input device 11 serving as an image input means, a printer 12 serving as a recording means, a computer 13 performing various kinds of processing, and an image input device 11. ), The printer 12 and the computer 13 schematically comprise two-way communication means 14, 15 to enable communication with each other.

The image input device 11 inputs color image information such as a face image into a color photograph (printed material) P1 as a digital image, and includes, for example, a digital camera, a video camera, a flatbed scanner, and the like. . In this embodiment, for example, a scanner is used.

The printer 12 outputs the recording P2 used as a personal authentication medium such as an ID card by recording color image information such as a face image and binary image such as a character. In this embodiment, the printer 12 is used as a dedicated printer.

The computer 13 is an image which is an image processing means for executing sub information embedding processing to generate composite image information by embedding sub information in a state where the sub information is not visible to the visual information input by the image input device 11. And a processor 16.

The computer 13 may be a personal computer or a dedicated board including a CPU, a semiconductor memory, a hard disk device, an image capture board, and the like. In this embodiment, a personal computer is used.

It should be noted that the image processor 16 of this embodiment is implemented by an application program module that executes a personal computer.

The bidirectional communication means 14 and 15 are not particularly limited as long as they send signals in both directions, and may include USB, SCSI, and the like. In this embodiment, USB 2.0 is used.

The overall operation of the image processing system including the above-described configuration and embedding sub information according to the first embodiment will be described with reference to the flowchart shown in FIG.

The image input device 11 inputs color image information such as a face image as main image information (step S1). The color image information is assumed to be the color face image of the photograph (printed material) P1. However, the present invention is not limited to this specific information. The input color image information is input to the image processor 16 of the computer 13.

The image processor 16 uses four color component information (images) of the ink index cyan (C), magenta (M), yellow (Y), and black (K), which are used to record the input color image information. At least three parts of information) (step S2). The image processor 16 rotates three color component information of cyan (C), magenta (M), and yellow (Y) obtained by color separation by a predetermined angle, respectively (step S3).

The image processor 16 embeds the sub information in the respective rotated color component information (step S4). Next, the image processor 16 rotates each part of the color component information in which the sub information is embedded in the same angle and in the opposite direction as in step S3 (step S5).

The image processor 16 generates the synthesized image information (color image information) by synthesizing the reversely rotated color component information (step S6), and transmits the generated synthesized image information to the printer 12. The printer 12 records the composite image information in which the sub-information is embedded on the recording medium, so as to obtain a recording P2 (step S7).

The embedding process (in step S4) in which the image processor 16 embeds sub information in each color component information will be described in detail below.

3 shows a configuration of main parts of the image processor 16. The image processor 16 includes a smoothing processor 21, a phase modulation processor 22, a chrominance modulation processor 23, a superposition processor 24, and a synthesis processor 25. These processors are modules of application programs that run on a personal computer. For example, the digital watermark processing method disclosed in Japanese Patent Laid-Open Nos. 11-168616 and 2001-268346 can be applied to the embedding process.

Each color component information 26 is one of the color-separated components of the image information associated with the color face image of the recording of this embodiment with the sub information 27 superimposed, rotated at a predetermined angle. Face image information is defined by forming pixels in lines in the vertical and horizontal directions of the image. This information has 24 bits (8 bits per R, G, or B component) information.

The sub information (embedded image information) 27 is obtained, for example, by converting the information to be embedded into binary image information, and corresponds to an identification number (ID number) or the like of the personal authentication medium. This information has one bit information per pixel.

The chrominance grid pattern 28 is a grid type pattern and is used as key information at the time of restoration of the sub information 27. This pattern has 1 bit information per pixel.

First, the smoothing processor 21 executes a smoothing process to have black pixel = " 1 " and white pixel = " 0 " In this case, the processor 21 extracts a plurality of pixel regions in the horizontal direction (x-direction) of the image and calculates a weighted average of these pixels.

The phase modulation processor 22 applies phase modulation to the chrominance grid pattern 28 based on the smoothing processing result of the smoothing processor 21. In this embodiment, the processor 22 rotates the 2x2 pixel pattern (the alternately appearing black and white pixels) 90 degrees clockwise.

The color difference modulation processor 23 executes the color difference modulation process using the color difference amount ΔCd preset based on the phase modulation result of the phase modulation processor 22. In this case, the processor 23 independently calculates three components cyan (C), magenta (M) and yellow (Y). For example, the color difference grid pattern 28 is a color difference grid pattern in which red-rich pixels (dot patterns) 2 and cyan-rich pixels (hatch patterns) 3 are repeatedly assigned as shown in FIG. In the case of 1), the C data is modulated by -ΔCd for the region corresponding to each pixel 2 rich in red, and the M and Y data are modulated by + ΔCd, corresponding to each pixel 3 rich in cyan. For the region, the C data is modulated by + ΔCd, and the M and Y data are modulated by -ΔCd.

The superposition processor 24 executes superposition processing using the color difference modulation processing result of the color difference modulation processor 23 and the respective parts of the color component information 26, so that the color difference grid modulated to each part of the color component information 26 is performed. The pattern 28 overlaps. Specifically, the C, M, and Y values of the color difference modulation processing result are added to the C, M, and Y values of respective portions of the color component information 26, respectively.

The synthesizing processor 25 rotates each portion of the color component information 26 superimposed with the chrominance grid pattern 28 at the same angle in the direction opposite to the rotation direction (in step S3), and reversely rotates the color component information ( Each part of 26 is synthesized to generate synthesized image information 29.

In the execution of the above-described embedding process, the sub information 27 may be superimposed on each part of the color component information 26. The composite image information 29 in which the sub information 27 is superimposed is transmitted to the printer 12, recorded on the recording medium, and obtains the recorded material P2.

5 and 6 show pixel array and sub information of the modulated chrominance grid pattern according to the first embodiment. In the region enclosed by the thick broken line in Fig. 5, two pixels 7a indicated by halftone dots and two pixels 7b indicated by hatches are alternately arranged, and a color difference grid having a configuration of 4 pixels by 2 lines is shown. The pattern 7 is shown.

As is known, with human visual characteristics, the distinguishable tone difference between pixels becomes smaller as the resolution is reduced, and the color difference value needs to assume a value according to the characteristic. In this embodiment, the color difference value ΔCd = “16” for embedding the sub information in a state where it cannot be seen.

The pixel 7a indicated by the halftone dots and the pixel 7b indicated by the hatch have a complementary color relationship. In this embodiment, the pixel 7a represented by the halftone dots is rich in red, and the pixel 7b represented by the hatch is rich in cyan as the complementary color of red.

The color difference grid pattern groups 8a, 8b, etc. of FIG. 5 have a 90 ° phase difference with neighboring color difference grid pattern groups. 6 shows an example of the sub information 9 which is a binary image defined by the black cell 9a and the white cell 9b (indicated by the hatch). The color difference grid pattern groups 8a and 8b of FIG. 5 are located at positions corresponding to the black cells 9a of FIG. That is, in this embodiment, the sub information 9 is superimposed on each color component information by modulating the phase of the color difference grid pattern.

7A to 7D are explanatory views for explaining individual color rotation processing (step S3), superposition (embedding) processing (step S4), and individual color reverse rotation processing (step S5). FIG. 7A shows a part of one color component information of color components separated by the color separation processing of step S2.

FIG. 7B shows one color component information obtained by rotating the color component information of FIG. 7A by 45 ° by the individual color rotation processing of step S3. The angle of FIG. 7B is 45 °, and the present embodiment shows magenta color component information. For example, the process for cyan color component information can perform the rotation process of 15 degrees angles.

As shown in FIG. 7B, the color difference grid pattern shown in FIG. 7C and modulated by the sub information is rotated color component information at a predetermined angle shown in FIG. 7B. Nested in FIG. 7D shows one color component information obtained by rotating the color component information of FIG. 7B overlaid with the color difference grid pattern by 45 ° reverse rotation in the individual color reverse rotation process of step S5.

As described above, the color difference grid pattern may be superimposed on the color component information tilted at a predetermined angle.

In the above description, each part of the color component information of cyan, magenta and yellow obtained by color separation is rotated at a predetermined angle, respectively, and the sub information is embedded in the respective rotated color component information. Each part of the color component information in which the sub information is embedded is rotated at the same angle in the opposite direction with respect to the above-described rotation, and each part of the color component information reversely rotated at the predetermined angle is recorded on the recording medium. However, processing opposite to the above-described processing may be executed, which will be described below.

FIG. 8A shows a part of one color component information of color components separated by color separation processing. FIG. 8B shows the color difference grid pattern modulated by the sub information, and FIG. 8C shows the color difference grid pattern obtained by rotating the pattern shown in FIG. 8B by 45 °. The angle in FIG. 8C is 45 °, and this embodiment shows magenta color component information. For example, the process of cyan color component information can perform a rotation process at an angle of 15 degrees.

The color difference grid pattern rotated at the predetermined angle shown in FIG. 8C is superimposed on the color component information shown in FIG. 8A. FIG. 8D shows one color component information superimposed with the color difference grid pattern by this superimposition process.

Also, with this processing, the color difference grid pattern tilted at a predetermined angle can be superimposed on each color component information, such as when the color difference grid pattern is superimposed on each color component information rotated at a predetermined angle.

9 shows an actual example of the recorded material P2 generated by the above-described image processing. The recorded material P2 is, for example, a personal authentication medium such as an ID card. The medium includes a face image 32a and a character image (personal management information, etc.) 32b for personal authentication. 31). Since the personal authentication medium needs to be evaluated for modulation and forgery, the sub information (star mark indicated by dotted lines) 33 obtained by modulating the color difference grid pattern 7 is superimposed on the face image 32a in an invisible state.

Note that the face image 32a is color image information, and the star mark as the sub information 33 is binary image information. Each color ink of yellow, magenta, cyan and black forming the color image information (face image 32a) is configured to have different preset angle tilts for each color, and the color difference grid pattern is different for each color. It is formed to have a tilt of the angle.

An image processing apparatus and an image processing method according to the first embodiment for reproducing sub information from the printed matter P2 generated as described above will be described later.

10 schematically shows the configuration of an image processing system to which an image processing apparatus and an image processing method for reproducing sub information from a printed matter according to the first embodiment are applied. This image processing system roughly communicates the image reading apparatus 41 as the reading means, the computer 43 which performs various kinds of processing, the image reading apparatus 41, the display device 42 and the computer 43 with each other. Bidirectional communication means 44 and 45 for connection.

The image reading device 41 reads color image information of a recording P2 such as a digital image, and includes a flatbed scanner, a digital camera, and the like. In this embodiment, for example, a scanner is used. The display device 42 displays and outputs various kinds of information such as reproduced sub information.

The computer 43 uses an image processor 46 which is image processing means for executing sub information reproduction processing to reproduce sub information embedded in the color image information from the color image information read by the image reading apparatus 41. Include.

It should be noted that the computer 43 may be a dedicated board or personal computer including a CPU, semiconductor memory, hard disk device, image capture board, and the like. In this embodiment, a personal computer is used.

It should be noted that the image processor 46 of this embodiment is implemented by a module of an application program running on a personal computer.

The bidirectional communication means 44 and 45 are not limited to specific ones as long as they carry signals in both directions, and may include USB, SCSI, and the like. In this embodiment, USB 2.0 is used.

The entire processing operation of the image processing system including the above-described configuration and reproducing sub information from the recording according to the first embodiment will be described below with reference to the flowchart shown in FIG.

The image reading device 41 reads the color image information of the recording P2 (step S11). The read color image information is input to the image processor 46 of the computer 43. The image processor 46 separates the input color image information into respective parts of the color component information of cyan (C), magenta (M), and yellow (Y), which are color inks forming the color image information (step S12). . It should be noted that the portion of color component information to be color separated may be red (R), green (G) and blue (B).

Next, the image processor 46 performs color-separated color component information of cyan (C), magenta (M), and yellow (Y) in a direction opposite to the pixel formation directions of yellow, cyan, and magenta forming color image information. Each part of is rotated at the same angle as the tilt angle of each color (step S13). Through this process, the pixel formation direction of each color can coincide with the vertical and horizontal directions of the image, and the pixel formation direction of the chrominance grid pattern can coincide with the vertical and horizontal directions of the image.

Next, the image processor 46 applies a process for extracting sub information to each part of the color component information reversely rotated at a predetermined angle, and extracts (reproduces) the sub information (step S14). The image processor 46 displays the extracted sub information on the display device 42 (step S15), and the operator checks the authenticity of the recording P2 based on the display of the sub information (step S16). .

In the above description, the extracted sub information is displayed on the display device 42, and the operator checks the authenticity of the recorded material P2, that is, the authenticity of the sub information based on the displayed content. However, the authenticity check can be done automatically and will be described later with reference to the flowchart shown in FIG.

Since the processing of steps S11 to S14 is the same as that shown in Fig. 11, a repetitive description thereof will be omitted, and only steps S17 to S19 different from Fig. 11 will be described.

When the sub information is extracted (reproduced) in step S14, the image processor 46 checks the extracted sub information with, for example, previously registered reference sub information (step S17), and the relationship in which the two sub information are preset The authenticity of the record P2 is checked by finding whether or not, i.e., the two sub-informations match in this example. The image processor 46 then displays the inspection result on the display device 42 (step S19).

It should be noted that the authenticity checking method of the record P2 is not limited to the above-described method, and other methods are also available. For example, authenticity can be checked by analyzing the extracted sub information. Alternatively, the authenticity of the record P2 may be checked based on the presence / absence of the sub information, instead of the authenticity check of the record P2 based on the authenticity of the sub information.

FIG. 13 shows a signal obtained by converting the color component information obtained by the process of step S13 of FIG. 11 into the spatial frequency domain. The horizontal axis shows the spatial frequency fx of the color component information in the horizontal direction, and the vertical axis shows the spatial frequency fy of the color component information in the vertical direction. The circular signal with a dot is a signal of the chrominance grid pattern 7.

In the reproduction processing of the sub information according to the first embodiment, the sub information 9 can be reproduced (extracted) by applying a band pass filter of a frequency corresponding to the signal of the chrominance grid pattern 7.

As described above, according to the first embodiment, the sub information can be superimposed on the color image information formed by tilting the pixel formation direction of each color component to have a predetermined angle, thereby modulating and counterfeiting the obtained recording. It can enhance resistance to

The second embodiment will be described below.

The second embodiment applies to the case of the second color image representation method previously described using Figs.

Since the configuration of the image processing system according to the second embodiment is the same as the configuration (FIG. 1) of the first embodiment, a repetitive description thereof will be omitted.

The overall operation of the image processing system according to the second embodiment will be described later with reference to the flowchart shown in FIG.

The image input device 11 inputs color image information such as a face image as main information (step S21). Assume that the color image information is the color face image of the photograph (printed material) P1. However, the present invention is not limited to this specific information. The input color image information is input to the image processor 16 of the computer 13.

The image processor 16 uses the input color image information as four parts of the color component information of the ink index cyan (C), magenta (M), yellow (Y) and black (K) used to record the color image information. (At least three parts of the image information). The image processor 16 allocates three pixels of the color component information of the visual C, the magenta M, and the yellow Y to have a predetermined angle (step S23).

 The image processor 16 embeds the sub information in the respective rotated color component information (step S24). Next, the image processor 16 allocates the pixels to restore the pixels by applying a process opposite to the process of step S23 to each part of the color component information in which the sub information is embedded (step S25).

The image processor 16 generates the synthesized image information (color image information) by synthesizing the portion of the color component information from which the pixel assignment is restored (step S26), and transmits the generated synthesized image information to the printer 12.

The printer 12 applies pseudo halftone processing to the composite image information in which the sub information is embedded using dither matrices for each part of the color component information (step S27), The recorded material P2 is obtained by recording the composite image information on which the pseudo halftone processing is performed on the recording medium (step S28).

An embedding process (process of step S24) for embedding sub information in each color component information by the image processor 16 will be described later with reference to FIG. 3 used in the first embodiment.

Each color component information 26 in the case of the second embodiment is information allocated by the individual color assignment processing in step S23, and sub information 27 is superimposed and associated with the color face image of the recording of this embodiment. One of the color-separated components of the image information. Note that face image information is defined by forming pixels in lines in the vertical and horizontal directions of the image. This information has information of 24 bits per pixel (8 bits per R, G, or B component).

The sub information (embedded image information) 27 is obtained by, for example, converting the information to be embedded into binary image information, and corresponds to an identification number (ID number) or the like of the personal authentication medium. This information has one bit of information per pixel.

The chrominance grid pattern 28 is a grid type pattern and is used as key information at the time of reproduction of the sub information 27. This pattern has 1 bit of information per pixel.

First, the smoothing processor 21 executes a smoothing process so that black pixel = "1" and white pixel = "0" of the sub information 27. In this case, the processor 21 extracts regions of the plurality of pixels in the horizontal direction (x-direction) of the image and calculates a weighted average of these pixels.

The phase modulation processor 22 applies phase modulation to the chrominance grid pattern 28 based on the smoothing processing result of the smoothing processor 21. In this embodiment, the processor 22 rotates the 2x2 pixel pattern (black and white pixels alternately) 90 ° clockwise.

The color difference modulation processor 23 executes color difference modulation processing using the color difference amount ΔCd preset based on the phase modulation result of the phase modulation processor 22. In this case, the processor 23 independently calculates three components cyan (C), magenta (M) and yellow (Y). For example, when the color difference grid pattern 28 is the color difference grid pattern 1 to which red-rich pixels (dotted patterns) 2 and cyan-rich pixels (hatch patterns) 3 are repeatedly assigned, As shown in FIG. 4, for the region corresponding to each pixel 2 rich in red, C data is modulated by -ΔCd, M and Y data is modulated by + ΔCd, and each pixel 3 rich in cyan C data is modulated by + ΔCd and M and Y data are modulated by -ΔCd for the region corresponding to.

The superimposition processor 24 performs superimposition processing using the color difference modulation processing result of the color difference modulation processor 23 and the respective parts of the color component information 26, and accordingly, the modulated color difference grid pattern 28 is colored. Each part of the component information 26 is superimposed. Specifically, the C, M, and Y values of the color difference modulation processing result are added to the C, M, and Y values of respective portions of the color component information 26, respectively.

The synthesizing processor 25 allocates the pixels to restore the pixels by applying the processing opposite to the processing of step S23 to each part of the color component information 26 superimposed with the chrominance grid pattern 28, and the pixel allocation is restored. Each part of the color component information 26 to be used is synthesize | combined, and the composite image information 29 is produced | generated accordingly.

In executing the above-described embedding process, the sub information 27 may be superimposed on the respective portions of the color component information 26. The composite image information 29 in which the sub information 27 is superimposed is transmitted to the printer 12, recorded on the recording medium, and the recorded material P2 is obtained.

Since the pixel array of the sub information and the modulated chrominance grid pattern according to the second embodiment is the same as the array of the first embodiment described above with reference to Figs. 5 and 6, the description thereof will be omitted.

15A and 15B are views for explaining the screen angle according to the second embodiment, and are enlarged views of one portion 5a of the color image 5 shown in FIG. In the second embodiment, the screen angles of cyan (C) and yellow (Y) are 18.4 ° and 108.4 °, respectively, and they have a difference of 90 °. Thus, as shown in Fig. 15A, cyan and yellow pixels are assigned to overlap each other. However, since the screen angle has a difference of 90 °, when cyan information is superimposed on yellow information, the cyan information may be superimposed to have a tilt at the screen angle corresponding to cyan so as to overlap the two information without disturbing the chrominance grid pattern. There is a need.

On the other hand, the screen angle of the magenta M is -18.4 °, and the cyan and magenta pixels overlap less with each other. For the chrominance grid pattern shown in Fig. 4, red and cyan-rich pixels need to be formed by superimposing pixels of three or more colors. In the recording method using the screening method, the pixels of the three colors overlap with each other less so as to disturb the color difference grid pattern, and the sub information cannot be superimposed on the color image information.

16, 17 and 18 show examples of critical matrices used to form screens (pixel arrays) corresponding to cyan, magenta and yellow.

16 shows the threshold matrix used to form the screen corresponding to cyan. The matrix 51a including the ten pixels indicated by the hatches in Fig. 16 is a unitary matrix and is a dither matrix used to represent pseudo tones. As shown in Fig. 16, by allocating the unit matrix 51a, as shown by the straight line 51b in Fig. 16, screen angle = 18.4 ° (angle in a clockwise direction from the horizontal direction in Fig. 16) can be realized. have.

17 shows the critical matrix used to form the screen corresponding to yellow. The matrix 51c including the ten pixels indicated by the hatch of FIG. 17 is a unit matrix, and is obtained by rotating the unit matrix 51a of FIG. 16 in a clockwise direction. By assigning the unit matrix 51c, as shown in FIG. 17, the screen angle = 108.4 ° is realized as indicated by the straight line 51d in FIG.

18 shows the critical matrix used to form the screen corresponding to magenta. The matrix 51e including the ten pixels indicated by the hatch of FIG. 18 is a unit matrix, and the unit matrix 51a of FIG. 16 is inverted (axis flipping horizontally) in axisymmetric with respect to the vertical direction of FIG. Get by By assigning the unit matrix 51e, as shown by the straight line 51f in FIG. 18, the screen angle = -18.4 ° is realized.

It should be noted that the screen angle is only an example and is not limited to the combination described above.

19, 20, 21, and 22 are explanatory diagrams showing the allocation processing, the superposition processing, the color difference grid pattern, and the individual color gamut allocation processing of portions of cyan and yellow color component information.

19 shows a pixel array of color component information of cyan and yellow, respectively. Each bold frame including the ten pixels of FIG. 19 represents a unit matrix of cyan. Reference numerals a1 to a4, b1 to b4, and c1 to c4 in FIG. 19 denote pixel blocks including nine pixels (3 × 3 pixels in the horizontal and vertical directions), respectively, and all of the groups a, b, and c are Cyan. Tilt to the corresponding screen angle. Yellow pixel blocks each including nine pixels are matched to cyan blocks, and cyan and the screen angles are different by 90 °, but these pixel blocks can be used in common.

20 illustrates a pixel array obtained by allocating pixels in FIG. 19, and pixel blocks each including nine pixels of FIG. 19 are linearly arranged to have each pixel block as a unit. The allocation process corresponding to cyan and yellow according to this embodiment is a process of allocating a pixel block to be rotated counterclockwise at a screen angle corresponding to cyan.

21 illustrates a color difference grid pattern. One pixel of the color difference grid pattern illustrated in FIG. 4 corresponds to a pixel block including nine pixels. That is, each pixel block (dot pattern in FIG. 21) 52 including nine pixels has a red-rich component, and each pixel block (hatch pattern in FIG. 21) including nine pixels is cyan. It has abundant ingredients. The color difference grid pattern shown in FIG. 21 is superimposed on the pixel array after assignment in FIG.

FIG. 22 shows a pixel array allocated to restore the original pixel array shown in FIG. 19 after the color difference grid pattern of FIG. 21 is superimposed on the pixel array of FIG. The recording unit according to this embodiment forms a screen corresponding to the color of the color component information. The screen is defined by a critical matrix and processed for each pixel block of the unit matrix. As shown in Fig. 21, since the chrominance grid pattern can be superimposed on a 9-pixel block in the unit matrix, the chrominance grid pattern is not disturbed even after the screen is formed.

As described above, the color difference grid pattern may be superimposed on the pixel block tilted at the screen angle corresponding to the cyan color component information. In addition, the color difference grid pattern may be superimposed on the pixel block tilted at a screen angle corresponding to a cyan different from the screen angle corresponding to yellow of the color component information of yellow.

23, 24, 25, and 26 are explanatory diagrams showing the process of assigning color component information of magenta, the superimposition process, the color difference grid pattern, and the individual color gamut assignment process.

Fig. 23 shows a pixel array of color component information of magenta. Each bold frame including 10 pixels of FIG. 23 represents a unit matrix of magenta. Reference numerals d1 to d4, e1 to d4, and f1 to f4 in FIG. 23 denote pixel blocks each containing nine pixels (3 × 3 pixels in the vertical and horizontal directions) forming a unit matrix, and d, e, and The f group is a group of pixel blocks selected such that the straight line (shown in FIG. 23) 54 connecting these groups and the angle θ made by the horizontal direction in FIG. 23 approach the screen angle corresponding to the cyan.

FIG. 24 shows a pixel array obtained by allocating the pixels in FIG. 23, and pixel blocks each including nine pixels in FIG. 23 are linearly arranged to have each pixel block as a unit. The allocation process corresponding to magenta according to this embodiment is a process of allocating pixel blocks by rearranging pixel blocks to be rotated counterclockwise at an angle close to the screen angle corresponding to cyan.

FIG. 25 shows the same color difference grid pattern as in FIG. 21, and the repetitive description thereof will be omitted. The color difference grid pattern in FIG. 25 is superimposed on the arranged pixel array. FIG. 26 shows a pixel array allocated to restore the original pixel array shown in FIG. 23 after the color difference grid pattern of FIG. 25 is superimposed on the pixel array of FIG. As shown in FIG. 26, the chrominance grid pattern is not disturbed even after the screen is formed because the chrominance grid pattern can be superimposed on the 9-pixel block in the unit matrix. In addition, since the color difference grid pattern can be superimposed so as to have a tilt angle close to the screen angle corresponding to cyan, the possibility that the pixels of three colors recorded by the recording unit overlap will increase, and the sub information will be colored image information. Can be nested reliably.

As described above, the color difference grid pattern may be superimposed on the pixel block of the color component information of magenta, which is different from the screen angle corresponding to magenta and tilted at an angle close to the screen angle corresponding to cyan. .

The recording P2 obtained by the second embodiment is the same as the recording of the first embodiment previously described using Fig. 9, and a repetitive description thereof will be omitted.

An image processing apparatus and an image processing method according to the second embodiment for reproducing sub information from the printed matter P2 generated as described above will be described later.

The configuration of the image processing system for reproducing sub information from the recording according to the second embodiment is the same as that of the image processing system (Fig. 10) described above according to the first embodiment, and the repetitive description thereof will be omitted.

The overall processing operation of the image processing system for reproducing sub information from the recording according to the second embodiment will be described later with reference to the flowchart shown in FIG.

The image reading device 41 reads the color image information of the recording P2 (step S31). The read color image information is input to the image processor 46 of the computer 43. The image processor 46 separates the input color image information into respective parts of the color component information of cyan (C), magenta (M), and yellow (Y) as color inks forming the color image information. It should be noted that the portion of color component information to be color separated may be red (R), green (G) and blue (B).

Next, the image processor 46 performs color separation of cyan (C), magenta (M) and yellow (Y) to have a predetermined angle in the same manner as in embedding the sub information (step S25 of FIG. 14). Pixels of respective parts of the component information are allocated (step S33).

The image processor 46 applies processing for extracting sub information to each assigned color component information to extract (reproduce) the sub information (step S34). Then, the image processor 46 displays the extracted sub information on the display device 42, and the operator checks the authenticity of the recorded material P2 based on the display of the sub information (step S36).

In the above description, the extracted sub information is displayed on the display device 42, and the operator checks the authenticity of the recorded material P2, that is, the authenticity of the sub information based on the displayed content. However, the authenticity check can be executed automatically, and will be described later with reference to the flowchart shown in FIG.

Since the processing of steps S31 to S34 is the same as that shown in Fig. 27, repeated description thereof will be omitted, and only steps S37 to S39 different from Fig. 27 will be described.

When the sub information is extracted (reproduced) in step S34, the image processor 46 checks the extracted sub information with, for example, previously registered reference sub information (step S37), and the relationship in which the two sub information is preset The authenticity of the recorded material P2 is checked by finding out whether or not there is, i.e., the two sub information matches in this example (step S38). The image processor 46 then displays the inspection result on the display device 42 (step S39).

It should be noted that the authenticity checking method of the record P2 is not limited to the above-described method, and other methods are also available. For example, authenticity can be checked by analyzing the extracted sub information. Alternatively, the authenticity of the record P2 may be checked based on the presence / absence of the sub information, instead of the authenticity check of the record P2 based on the authenticity of the sub information.

As described above, according to the second embodiment, the sub information can be superimposed on the color image information formed by tilting the pixel formation direction of each color component so as to have a predetermined angle, thereby modulating and forging the obtained recordings. It can enhance resistance to

In the description of the above embodiment, color image information such as a face image is input, and the input color image information is separated into portions of the color image information of C, M, and Y, and each portion of the color separated color component information of the colors is separated. Subsequent processing is applied. However, the invention is not limited to these specific embodiments. According to the present invention, the image information of three or more colors as main information, for example, the portion of the externally color separated color component information of C, M and Y, and the subsequent processing of the input color component information of the color When applied to each part, the same action and effect can be obtained.

Additional advantages and modifications can readily occur to those skilled in the art. Therefore, the invention is not to be limited in scope and to the exemplary embodiments and details shown and described herein. Accordingly, various modifications may be made without departing from the spirit and scope of the inventive concept as defined by the appended claims and their equivalents.

1 is a schematic block diagram showing the configuration of an image processing system to which an image processing apparatus and an image processing method for embedding sub information according to the first embodiment are applied;

Fig. 2 is a flowchart for explaining the overall processing operation of the image processing system for embedding sub information according to the first embodiment.

3 is a schematic block diagram showing a configuration of main parts of an image processor;

4 is a diagram illustrating an example of a color difference grid pattern.

5 is a diagram illustrating a pixel array of a chrominance grid pattern.

6 is a diagram for explaining sub information.

7A to 7D are views showing individual color rotation processing, superposition (embedding) processing, and individual color reverse rotation processing.

8A to 8D are diagrams illustrating another process of superimposing sub information on respective color component information.

Fig. 9 is a diagram showing a practical example of the generated record.

Fig. 10 is a schematic block diagram showing a configuration of an image processing system to which an image processing apparatus and an image processing method for reproducing sub information from a recorded material according to the first embodiment are applied.

Fig. 11 is a flowchart for explaining the overall operation of the image processing system for reproducing sub information from a recording according to the first embodiment.

Fig. 12 is a flowchart for explaining another example of the entire processing operation of the image processing system for reproducing sub information from the recording according to the first embodiment.

Fig. 13 is a diagram showing a frequency signal of image information obtained by scanning a face image of a generated printed matter.

Fig. 14 is a flowchart for explaining the overall processing operation of the image processing system for embedding sub information according to the second embodiment.

15A and 15B illustrate a screen angle according to a second embodiment.

Fig. 16 is an explanatory diagram of a critical matrix used to form the screen according to the second embodiment.

17 is an explanatory diagram of a critical matrix used to form the screen according to the second embodiment.

18 is an explanatory diagram of a threshold matrix used to form a screen according to the second embodiment.

19 is a diagram showing an example of a pixel array of an image according to the second embodiment.

20 is a diagram showing an example of a pixel array allocated by individual color assignment processing according to the second embodiment.

21 is a diagram showing an example of a color difference grid pattern according to the second embodiment.

Fig. 22 is a diagram showing an example of a pixel array of an image after embedding of sub information according to the second embodiment.

23 is a diagram showing an example of a pixel array according to the second embodiment.

FIG. 24 is a diagram showing an example of a pixel array allocated by individual color assignment processing according to the second embodiment. FIG.

25 is a diagram showing an example of a color difference grid pattern according to the second embodiment.

Fig. 26 is a diagram showing an example of a pixel array after embedding of sub information according to the second embodiment.

Fig. 27 is a flowchart for explaining the overall operation of the image processing system for reproducing sub information from a recording according to the second embodiment.

FIG. 28 is a flowchart showing another example of the entire processing operation of the image processing system for reproducing sub information from a recording according to the second embodiment;

Fig. 29 is a diagram showing an example of a color image formed in a green leaf by the electrophotographic method.

FIG. 30 is an enlarged view showing a part of the color image of FIG. 29; FIG.

FIG. 31 is a diagram showing respective separated color component information of FIG. 30; FIG.

FIG. 32 is an enlarged view showing a part of the color image of FIG. 29; FIG.

FIG. 33 is a diagram showing respective separated color component information of FIG. 32; FIG.

<Explanation of symbols for the main parts of the drawings>

11: Image input value

12: printer

13: computer

16: picture processor

Claims (21)

As an image processing apparatus, Image input means for inputting main image information defined by first, second and third color component information corresponding to at least three colors; Modulating means for modulating a chrominance grid pattern with sub information; After rotating the modulated chrominance grid pattern and each of the first, second, and third color component information with respect to each other at a predetermined angle, the modulated chrominance grid pattern is rotated with respect to the first, second, and third color components. Superimposing means for superposing each of the information; Combining means for synthesizing the first, second and third color component information superimposed with the modulated chrominance grid pattern to produce color image information Image processing apparatus comprising a. The method of claim 1, The superimposing means relatively rotates the first color component information and the modulated chrominance grid pattern at a first rotational angle in a preset rotational direction, and the second color component information and the modulated chrominance grid pattern Relatively rotate at a second rotation angle in a rotation direction, relatively rotate the third color component information and the modulated chrominance grid pattern at a third rotation angle in the preset rotation direction, and then modulate the modulated chrominance grid pattern Is superimposed on the first color component information, the second color component information, and the third color component information, respectively, The synthesizing means rotates the first color component information superimposed with the chrominance grid pattern at the first rotation angle in a direction opposite to the preset rotation direction, and converts the second color component information superimposed with the chrominance grid pattern. For rotating at the second rotation angle in a direction opposite to the preset rotation direction, and for rotating the third color component information overlapping the chrominance grid pattern at the third rotation angle in a direction opposite to the preset rotation direction. And first processing means and second processing means for synthesizing the first, second and third color component information rotating in the opposite direction. The method of claim 1, The superimposing means rotates the modulated chrominance grid pattern and the modulated chrominance grid pattern of the first, second and third color component information, and then converts the modulated and rotated chrominance grid pattern into the first, second and third colors. An image processing apparatus superimposed on each of the third color component information. The method of claim 1, And recording means for recording the color image information on a recording medium. As the image processing method, Inputting main image information defined by first, second and third color component information corresponding to at least three colors; Each of the color difference grid patterns modulated with sub information and the first, second and third color component information are rotated with respect to each other at a predetermined angle, and then the modulated color difference grid patterns are rotated with respect to the first, second and third. Superimposing each of the color component information, Synthesizing the first, second, and third color component information superimposed with the modulated chrominance grid pattern to produce color image information Image processing method comprising a. The method of claim 5, The first color component information and the modulated chrominance grid pattern are relatively rotated at a first rotational angle in a predetermined rotation direction, and the second color component information and the modulated chrominance grid pattern are generated in the predetermined rotation direction. Relatively rotate at a second rotation angle, the third color component information and the modulated chrominance grid pattern are relatively rotated at a third rotation angle in the preset rotation direction, and then the modulated chrominance grid pattern is formed in the first rotation angle. Superimposed on color component information, the second color component information, and the third color component information, respectively, The first color component information overlapping the chrominance grid pattern is rotated at the first rotation angle in a direction opposite to the preset rotation direction, and the second color component information overlapping the chrominance grid pattern is the preset The third color component information, which rotates at the second rotation angle in a direction opposite to the rotation direction, and overlaps the color difference grid pattern, rotates at the third rotation angle in a direction opposite to the preset rotation direction, and in the opposite direction. And the first, second and third color component information which rotates with each other. As a recording in which color image information is recorded, The color image information, The chrominance grid pattern modulated by the sub information and the first, second and third color component information which define main image information and respectively correspond to at least three colors are rotated with respect to each other at a predetermined angle, and then modulated. Superimposing a chrominance grid pattern on each of the first, second and third color component information, By synthesizing the first, second and third color component information superimposed with the modulated chrominance grid pattern to produce color image information, A record, which is information generated. The method of claim 7, wherein The color image information, Relatively rotate the first color component information and the modulated chrominance grid pattern at a first rotational angle in a predetermined rotation direction, and adjust the second color component information and the modulated chrominance grid pattern in the predetermined rotational direction. Relatively rotate at a second rotation angle, relatively rotate the third color component information and the modulated chrominance grid pattern at a third rotation angle in the preset rotation direction, and then rotate the modulated chrominance grid pattern to the first Superimposed on color component information, the second color component information, and the third color component information, respectively, Rotate the first color component information superimposed with the chrominance grid pattern at the first rotation angle in a direction opposite to the preset rotational direction, and rotate the second color component information superimposed with the chrominance grid pattern with the preset rotation Rotates the second color angle in a direction opposite to the direction, and rotates the third color component information overlapping the color difference grid pattern at the third rotation angle in a direction opposite to the preset rotation direction, and in the opposite direction. By synthesizing the rotating first, second and third color component information, A record, which is information generated. The chrominance grid pattern modulated by the sub information and the first, second and third color component information which define main image information and respectively correspond to at least three colors are rotated with respect to each other at a predetermined angle, and then modulated. Superimpose a chrominance grid pattern on each of the first, second, and third color component information, and synthesize the first, second, and third color component information superimposed with the modulated chrominance grid pattern to generate color image information. An image processing apparatus which processes color image information that is information generated by Reading means for reading the color image information from a recording in which the color image information is recorded; Color separation means for separating the first, second and third color component information from the color image information; Separate color rotation means for rotating the first, second and third color component information at a predetermined angle; Sub information extraction means for extracting the sub information from the rotated first, second and third color component information based on the color difference grid pattern Image processing apparatus comprising a. 10. The method of claim 9, And authenticity checking means for checking the authenticity of the recording based on the extraction result of the sub information. The chrominance grid pattern modulated by the sub information and the first, second and third color component information which define main image information and respectively correspond to at least three colors are rotated with respect to each other at a predetermined angle, and then modulated. Superimpose a chrominance grid pattern on each of the first, second, and third color component information, and synthesize the first, second, and third color component information superimposed with the modulated chrominance grid pattern to generate color image information. An image processing method for processing color image information that is information generated by Reading the color image information from a recording in which the color image information is recorded; Separating the first, second and third color component information from the color image information; Rotating the first, second and third color component information at a predetermined angle; Extracting the sub information from the rotated first, second and third color component information based on the color difference grid pattern. Image processing method comprising a. The method of claim 11, And checking the authenticity of the recording based on the extraction result of the sub information. As an image forming apparatus, Image input means for inputting main image information defined by first, second and third color component information corresponding to at least three colors; First allocation processing for allocating a plurality of first unit matrices included in the first threshold matrix for forming the first color component information according to a first screen angle, and a second threshold for forming the second color component information Second allocation processing for allocating a plurality of second unit matrices included in the matrix according to the second screen angle, and a plurality of third unit matrices included in the third threshold matrix forming the third color component information. First assigning means for executing third assigning processing for allocating according to the three screen angles; Modulating means for modulating a chrominance grid pattern with sub information; Superimposing means for superimposing the modulated chrominance grid pattern on the first, second and third color component information; And individually forming the plurality of first unit matrices included in the first color component information by performing allocation processing opposite to the first allocation processing on the first color component information overlapping the modulated color difference grid pattern. Restoring original allocation of the plurality of pixel blocks, and performing allocation processing that is opposite to the second allocation processing on the second color component information overlapping the modulated color difference grid pattern and included in the second color component information. An original assignment of a plurality of pixel blocks that individually form the plurality of second unit matrices, and an assignment that is opposite to the third allocation processing for the third color component information overlapping the modulated chrominance grid pattern Executes processing to individually separate the plurality of third unit matrices included in the third color component information. And reverse allocation means for restoring the original allocation of a plurality of pixel blocks formed by, Synthesizing means for synthesizing the first, second, and third color component information respectively formed of the plurality of pixel blocks reconstructed to the original assignment to generate color image information; Pseudo halftones for applying pseudo halftones to the first, second and third color component information defining the color image information using the first threshold matrix, the second threshold matrix and the third threshold matrix. Sudan, Recording means for recording the color image information on a recording medium Image forming apparatus comprising a. The method of claim 13, The first, second and third color component information correspond to portions of color component information which are yellow, magenta and cyan, respectively, The first assigning means assigns the plurality of pixel blocks forming the second color component information at an angle different from the second screen angle, and assigns the plurality of pixel blocks forming the first color component information to the first pixel block. The plurality of pixel blocks which are assigned at an angle different from one screen angle or which form the third color component information at an angle different from the third screen angle, and which form the first color component information. And an image forming apparatus for allocating a pixel block at an angle different from the first screen angle. The method of claim 13, The first, second and third color component information correspond to portions of color component information which are yellow, magenta and cyan, respectively, And the first screen angle and the third screen angle are orthogonal, or the first screen angle and the second screen angle are orthogonal. As the image forming method, Inputting main image information defined by first, second and third color component information corresponding to at least three colors; First allocation processing for allocating a plurality of first unit matrices included in the first threshold matrix for forming the first color component information according to a first screen angle, and a second threshold for forming the second color component information Second allocation processing for allocating a plurality of second unit matrices included in the matrix according to the second screen angle, and a plurality of third unit matrices included in the third threshold matrix forming the third color component information. Performing third allocation processing for allocating according to the three screen angles; Superimposing a color difference grid pattern modulated with sub information onto the first, second and third color component information; And individually forming the plurality of first unit matrices included in the first color component information by performing allocation processing opposite to the first allocation processing on the first color component information overlapping the modulated color difference grid pattern. Restoring original allocation of the plurality of pixel blocks, and performing allocation processing that is opposite to the second allocation processing on the second color component information overlapping the modulated color difference grid pattern and included in the second color component information. An original assignment of a plurality of pixel blocks that individually form the plurality of second unit matrices, and an assignment that is opposite to the third allocation processing for the third color component information overlapping the modulated chrominance grid pattern Executes processing to individually separate the plurality of third unit matrices included in the third color component information. And a step of reconstructing a plurality of original allocation of pixel blocks forming a, Synthesizing the first, second, and third color component information, each of which is formed of the plurality of pixel blocks restored to the original assignment, to generate color image information; Applying pseudo halftones to the first, second and third color component information defining the color image information using the first, second and third threshold matrices; Recording the color image information on a recording medium Image forming method comprising a. As a recording in which color image information is recorded, The color image information, A plurality of firsts included in a first threshold matrix defining main image information and forming first color component information among first color component information, second color component information, and third color component information corresponding to at least three colors; First allocation processing for allocating a unitary matrix according to a first screen angle, and for allocating a plurality of second unit matrices included in a second critical matrix forming the second color component information according to a second screen angle Perform second allocation processing and third allocation processing for allocating a plurality of third unit matrices included in a third threshold matrix forming the third color component information according to a third screen angle, A color difference grid pattern modulated with sub information is superimposed on the first, second and third color component information, And individually forming the plurality of first unit matrices included in the first color component information by performing allocation processing opposite to the first allocation processing on the first color component information overlapping the modulated color difference grid pattern. Restoring original allocation of the plurality of pixel blocks, and performing allocation processing that is opposite to the second allocation processing on the second color component information overlapping the modulated color difference grid pattern and included in the second color component information. An original assignment of a plurality of pixel blocks that individually form the plurality of second unit matrices, and an assignment that is opposite to the third allocation processing for the third color component information overlapping the modulated chrominance grid pattern Executes processing to individually separate the plurality of third unit matrices included in the third color component information. Restoring a plurality of original allocation of a pixel block formed of a and, Synthesize the first, second and third color component information respectively formed of the plurality of pixel blocks reconstructed to the original assignment to generate color image information, By applying pseudo halftones to the first, second and third color component information defining the color image information using the first, second and third threshold matrices, A record, which is information generated. A plurality of firsts included in a first threshold matrix defining main image information and forming first color component information among first color component information, second color component information, and third color component information corresponding to at least three colors; First allocation processing for allocating a unitary matrix according to a first screen angle, and for allocating a plurality of second unit matrices included in a second critical matrix forming the second color component information according to a second screen angle Perform second allocation processing and third allocation processing for allocating a plurality of third unit matrices included in a third threshold matrix forming the third color component information according to a third screen angle, A color difference grid pattern modulated with sub information is superimposed on the first, second and third color component information, And individually forming the plurality of first unit matrices included in the first color component information by performing allocation processing opposite to the first allocation processing on the first color component information overlapping the modulated color difference grid pattern. Restoring original allocation of the plurality of pixel blocks, and performing allocation processing that is opposite to the second allocation processing on the second color component information overlapping the modulated color difference grid pattern and included in the second color component information. An original assignment of a plurality of pixel blocks that individually form the plurality of second unit matrices, and an assignment that is opposite to the third allocation processing for the third color component information overlapping the modulated chrominance grid pattern Executes processing to individually separate the plurality of third unit matrices included in the third color component information. Restoring a plurality of original allocation of a pixel block formed of a and, Synthesize the first, second and third color component information respectively formed of the plurality of pixel blocks reconstructed to the original assignment to generate color image information, By applying pseudo halftones to the first, second and third color component information defining the color image information using the first, second and third threshold matrices, An image forming apparatus which processes color image information that is generated information, Reading means for reading the color image information from a recording in which the color image information is recorded; Color separation means for separating the first, second and third color component information from the color image information; The first allocation processing for allocating the plurality of first unit matrices included in the first critical matrix for forming the first color component information according to the first screen angle, and forming the second color component information The second allocation processing for allocating the plurality of second unit matrices included in the second threshold matrix according to the second screen angle, and in the third threshold matrix forming the third color component information. Second allocation means for executing the third allocation processing for allocating the plurality of third unit matrices according to the third screen angle; Sub information extracting means for extracting the sub information from the rotated first, second and third color component information allocated by the first, second and third allocation processing, respectively, based on the chrominance grid pattern; Comprising an image forming apparatus. The method of claim 18, And authenticity checking means for checking the authenticity of the recording based on the extraction result of the sub information. A plurality of firsts included in a first threshold matrix defining main image information and forming first color component information among first color component information, second color component information, and third color component information corresponding to at least three colors; First allocation processing for allocating a unitary matrix according to a first screen angle, and for allocating a plurality of second unit matrices included in a second critical matrix forming the second color component information according to a second screen angle Perform second allocation processing and third allocation processing for allocating a plurality of third unit matrices included in a third threshold matrix forming the third color component information according to a third screen angle, A color difference grid pattern modulated with sub information is superimposed on the first, second and third color component information, And individually forming the plurality of first unit matrices included in the first color component information by performing allocation processing opposite to the first allocation processing on the first color component information overlapping the modulated color difference grid pattern. Restoring original allocation of the plurality of pixel blocks, and performing allocation processing that is opposite to the second allocation processing on the second color component information overlapping the modulated color difference grid pattern and included in the second color component information. An original assignment of a plurality of pixel blocks that individually form the plurality of second unit matrices, and an assignment that is opposite to the third allocation processing for the third color component information overlapping the modulated chrominance grid pattern Executes processing to individually separate the plurality of third unit matrices included in the third color component information. Restoring a plurality of original allocation of a pixel block formed of a and, Synthesize the first, second and third color component information respectively formed of the plurality of pixel blocks reconstructed to the original assignment to generate color image information, By applying pseudo halftones to the first, second and third color component information defining the color image information using the first, second and third threshold matrices, An image forming method for processing color image information that is generated information, Reading the color image information from a recording in which the color image information is recorded; Separating the first, second and third color component information from the color image information; The first allocation processing for allocating the plurality of first unit matrices included in the first critical matrix for forming the first color component information according to the first screen angle, and forming the second color component information The second allocation processing for allocating the plurality of second unit matrices included in the second threshold matrix according to the second screen angle, and in the third threshold matrix forming the third color component information. Performing the third allocation processing to assign the plurality of third unit matrices according to the third screen angle; Extracting the sub information from the rotated first, second and third color component information allocated by the first, second and third allocation processing, respectively, based on the chrominance grid pattern. Image forming method comprising a. The method of claim 20, And checking the authenticity of the recording based on the extraction result of the sub information.

Images